The most appropriate answer can depend on how the people you are selling UX to currently approaches design.
Do they approach it as marketing? As development? As web design / graphic design? Find names in those fields that they would know, and draw out points that those people make which have relevance to UX. Don't force UX buzzwords on them; start by tying the buzzwords that they are using into principles in our field.
An industry that I try to sell UX to - which mostly doesn't do user-centered design, even though some company names in this industry would shock you because of how user-centered you may think they would be - approaches design in several different ways.
I deal with digital products - websites and software. For clients that describe their current web effort as digital marketing, and have their existing site designed by a local or industry-specific marketing firm, I should be using the language of digital marketing. Similarly, others see websites as a graphic designer's domain, which means that I should meet them there before interweaving UX into our discussions. And likewise for those who see it as web development, customer service, and so on.
The industry that I am trying to sell to actually talks a lot about guest experience rather than user experience, so I'm also looking at how to tie that into convincing prospects to invest in digital UX design. As I learn more about it, I might write some articles about that for my own site and send them to prospects.
For those who see design as primarily marketing: I can't recommend Seth Godin highly enough. He has written a ton over the years (check out his books too), but here are some posts related to user experience that don't use UX jargon:
- The most important rule
- The thermostat and the frying pan
- Four questions worth answering
For those who see it as development: Coding Horror is a more technically-focused blog written from a development perspective, but it also has some good reads:
- Selling Usability (more for you than for the people you are selling it to, but some good ideas here)
- The Cost of Complexity
- Sharing the Customer's Pain
For graphic design, I think someone else should answer since I have less familiarity with that.